This is wax on composition board.The disc has 5 large radial cracks which
probably render it mechanically unplayable.The groove modulation is vertical and the grooveis very wide relative to the later commercial
cylinders.

Image from 287700 near the intersection of two cracks

Pitch 600 microns

Depth 95 microns

Amplitude 10 microns

Partial audio extractions in chronological : order: Low pass
filter applied to all.Additional noise
reduction applied to the last two files. Speed set to 20 rpm.